You may have curling or buckling shingles for a number of reasons but the common denominator is moisture.
Shingles bulging up does that mean roof is leaking.
If you have gutters but no gutter apron to stop the water it will wick behind the gutter.
Repairing a roof leak is not always difficult.
Roof shingles are not lying flat.
One can see clearly lots of ripples bumps all over the roof but one section is much worse than the rest.
However they can cause leaks particularly if you have an asphalt shingle roof.
Eventually the fascia soffits and even the roof sheathing will rot.
Those ripples bumps can be pressed down easily which suggests that there is space between the shingle and decking i e shingles are not properly supported by the decking where there are ripples.
If your roof is old enough you may need to replace it entirely.
When water flows off the edge of your roof some of it clings to the underside of the shingles and dribbles toward the fascia.
They usually aren t the first place you should look for a leak but once they are old and worn enough they can become a problem.
If you had a roof replacement recently but kept the same roof decking the wood may have absorbed moisture before the new roof was installed.
Corroded cracked broken and missing shingles cause leaks and may need to be repaired.
Moisture is detrimental to a roofing system.
Lumpy bumpy or curling shingles that do not.
When plywood or osb sheathing picks up moisture it expands.
The shingles on your roof serve a dual purpose.
They give the roof a finished look while forming a protective seal.
Shingles don t last forever.
The most common cause appears to be movement in the roof sheathing with changes in moisture levels.
The decking will rot from continuous exposure to water which would seriously damage your home.
However if you put the screws through the shingles then you will have the perfect storm for leaks all over your roof.
If the sheathing is properly gapped then the gaps can close causing the shingles spanning the gap to buckle.
Roofing nails sticking up called nail pops might look like an unimportant issue.
This video walks through repairi.
The decking can also buckle if it is not fastened to the framing correctly or if water leaks beneath the roof s shingles.